A pneumatic tool is a tool that outputs an operating power through driving a pneumatic motor by compressed air provided by an air compressor. Featuring advantages of having fast motions and strong adaptivity for operability in harsh environments such flammable, explosive, humid and impact-receiving environments, being zero-pollution, as well as having a long life cycle, a simple structure and easy maintenance, pneumatic tools are extensively applied in various fields including modern machinery manufacturing, shipbuilding, vehicle manufacturing, vehicle maintenance, building and decorating, and stone processing.
For example, the Taiwan Patent No. M457617, “Pneumatic Tool”, includes a housing, a driving mechanism and an air control mechanism. The housing includes an assembly space and an air entering channel in communication with the assembly space. The driving mechanism, installed in the assembly space of the housing, includes a cylinder block, and a forward rotation channel and a reverse rotation channel in communication with the cylinder. The air control mechanism includes an air control valve installed in the air entering channel and connected correspondingly to the cylinder block, and a control lever seat that drives the air control valve to rotate along a rotation center. The air control valve includes an air control channel that rotates and corresponds to the forward rotation channel and the reverse rotation channel of the cylinder block.
However, when the housing of the pneumatic tool is manufactured, the air control channel is manufactured through a sand core mold. More specifically, during the manufacturing process of the housing, sand is first buried at a position of the air control channel, and the sand buried at the position of the air control channel is then removed when the housing has been manufactured to further form the air control channel. During the manufacturing process of the housing, a collapse is likely caused due to an inappropriate amount of sand buried or an inadequate strength of the sand core. As a result, defects including a non-uniform size of the air control channel or the failure of connecting to the cylinder block may be produced, leading to a lowered yield rate. Therefore, it is a goal of manufacturers of the technical field to provide a solution that reduces defects of the air control channel.